Method of molding scale arms



7 Jan. 1, 1929.

A. P. HOPKINS METHOD OF MOLDING SCALE ARMS 2 Sh ms-Sheet l Filed Dec. 21, 1927 ATTORNEY A. P. HOPKINS METHOD or MOLDING SCALE ARMS.

Jan. 1, 1929.

File d Dec. 21. 1927 2 Sheets ATTORNEY Patented Jan. 1, 1929.

UNITED- STATES PATENT OFFICE.

i 7 v ANTHONY PEARSON HOPKINS, OF RU'ILAND, VERMONT, ASSIGNOR TO THE HOWE SCALE COMPANY, OF RUTLAND, VERMONT, A CORPORATION OF VERMONT.

METHOD OF MOLDING'SCALE ARMS.

Application filed December 21, 1927. Serial No. 241,541.

This invention relates to new and useful improvements in the method of and mold for casting weighing scale levers or arms having knife edge pivots.

Weighing scale levers or arms are generally provided with knife edge pivots, and there may be either one or more of these pivots located at each end of the lever. In order for the scale to function properly, it is necessary for the knife edges of the pivots at the opposite ends of the lever to be in exact longitudinal alinement and in the same horizontal plane. When-a lever is provided with two or more knife edge pivots at each end thereof, it is also necessary for the knife edges at each end to be located in exact parallelism.

Among the several objects of my invention are to provide a method of casting weighing scale levers having one or more knife edge pivots at each end whereby the edges of the pivots at the opposite ends of the lever Wlll be positively located in exact longitudinal alinement and in the same horizontal plane, or whereby when \two pivots are located at each end of the lever, the edges of each pair of pivots will be positively located in parallelism and in the same horizontal plane; and to provide a mold for carrying out my method in which dry sand cores for supporting the knife edge pivots or inserts are provided whereby the pivots will be maintained in definite predetermined relation during the molding operation.

With these'and other objects in view which will more fully appear, the nature of the invention will be more clearly understood by following the description, the appended claims, and the several views illustrated in the accompanying drawings.

lln the accompanying drawings which il lustrate my method and mold:

Figure 1 is a perspective view of a completed scale lever constructed inaccordance with my invention,

Figure 2 is a plan view of a drag for easting two levers simultaneously, the view show-- ing a completed casting with the upper core sections removed, and a mold cavity and the dry sand cores in position and supporting the knife edge pivot inserts,

Figure 3 is a vertical cross sectional view taken on the line 33 of Figure 2,

Figure 4 is a vertical longitudinal sectional view taken on the line 4-4 of Figure 2,

Figure 5 is a vertical sectional view taken on the line 5-5 of Figure 2, I

Figure 6 is a perspective view of one of the dry sand cores showing the knife edge pivots in position between the upper and lower 86G- tions thereof,

Figure 7 is a perspective per section, and

Figure 8 is a perspective view of the lower section with the pivots in position thereon.

Like reference numerals designate corresponding parts throughout the several figures of the drawings. 1'

My improved method relates to the casting of a weighing scale lever or arm A, such as is shown in Fig. 1, although it will be understood that this particular showing is for illustrative purposes only, and is not intended as a limitation. This scale lever .includes a view of the upcomparatively long arm 5 of cast metal having jaws 6 6 at its opposite ends, each jaw including longitudinally extending side walls 7-7 and transverse walls 8-8. Supported by the transverse walls 88 of each jaw is a .pair of knife edge pivots 99 of hardened each pivot is in'a Vertical plane, that is, a

plane extending at right angles to the hori zontal plane containing the knife edges of one pair of pivots. Each pivot includes a semi-circular base 9 and tapered side faces 9"-9 which merge to form theknife edges 10.

In carryin out my method, I first fill the cope l1 and t 1e drag 12 which form the mold B, with green sand, and then by successive operations form the mold cavities in said cope and drag by a pattern (not shown). Each cavity includes spaced end portions 1414;-

in which the jaws 6' are cast, and an intermediate connecting portion 15 in which the lever arm 5 is cast integral with the jaws. Each end portion 14 is centrally formed with a. core print 15 whichis angular in plan view. I then place a dry sand core 16 in each print of the drag and support a pair of the knife edge pivots-9 on each core 16.

' Each dry sand core is divided horizontally along the stepped line (iv-w to form upper and lower angular sections 17-17 which are counterparts of each other and are therefore interchangeable. Each section, therefore, includes a projecting portion 18, and a seat portion 19 which arejoined by a transversely disposedinclind step 17 the projecting por tion 18 of one section fitting against the seat portion 19 of the other section. Formed in the inner face of the projecting portion 18 of each section is a transversely disposed groove or seat 20, and formed in the inner face of the seat portion 19 of each section is a transversely disposed groove or seat 21.

Each groove 20 is V-shaped in cross-section to' receive in close fitting relation the inclined faces 9" b of a pivot, and each groove21 is semi-circular .in cross-section to receive in closen'elation the semi-circular base 9 of a downwardly.

pivot. Thus the meeting or inner faces of the sections 17-17 of each core are conjointly formed with transversely disposed horizontal seats for receiving a pair of pivots 9,

whereby the knife edges are maintained in parallelism and in the same horizontal plane, one edge projecting upwardly and the other The side faces 22-22 and the end faces 23-23 of each section, are beveled towards the meetingor inner face in order to permit easy removal of the section from the casting. The outer edge along the sides and ends are beveled as'at- 2424 and 25'25 respectively to insure accurate seating of the sections in the respective prints 1515 of the cope and drag.

After placing thelower section of each dry sand core 16 in each print 15 of the drag, I then position the two pivots 9-9 in the respective seats 20 and 21, and then position the upper core sections upon the lower core secvtions, the projecting portions of the pivots 9-9 being received by the corresponding grooves or'seats 20 and 21.- The V-shaped grooves 20function to center the knife edges 10 relative to the semi-circular seats 21, and thereby position and maintain the pivots with their major axes in parallel vertical planes. The pivots are thus held against movement and consequently the knife edges 10 of all pivots will be positioned and maintained in the proper relation describedabove.

I then position the cops on the drag and pour molten metal into the mold in the usual Way; The casting A is then removed from the mold and the dry sand cores 16-16 are removed fromthe jaws 66 of the casting.

out departing from the spirit and scope of my invention.

I claim:

. 1. The method of casting a scale lever having alined pivots,.consisting in filling the cope and drag 'of a mold with green sand, then forming in the. cope and drag respectively .a mold cavity having core prints located in predetermined relation, then p0- sitioning dry sand cores in the respective prints of the drag and positioning knife edge pivots on the cores with the knife edges.

in longitudinal alinement and in a common plane, then positioning the cope on the drag, and finally pouring the mold.

2. A mold for casting weighing scale levers having knife edge pivots, comprising a drag and a cope each being'formed with a mold cavity having spaced end portions and a connecting portion, the end portions being respectively formed with a core print, dry sand cores respectively positioned in the opposed prints-of the end portionsand knife edge pivots supported and maintained onsaid cores in longitudinal alinement.

3. A mold for casting weighing scale levers having knife edge pivots, comprising a drag and. a cope each being formed with a mold cavity having spaced end portions and a connecting portion, the end portions being respectively formed with a core print, dry sand cores respectively positioned in the opposed prints of the end portions, each core comprising upper and'lower sections having a horizontal seat conjointly formed in their meeting faces, and knife edge pivots mounted in said seats and maintained thereby in longitudinal alinement.

4. A mold for casting weighing scale levers having knife edge pivots, comprising a drag and a cope each being formed with a mold cavity having spaced end portions and a connecting portion, the end portions being respectively formed with a core print, dry 1 sand cores respectively positioned in the opposed prints of the end portions, each core comprising upper and lower sections having stepped meeting faces forming a resultant projecting portion and a seat portion, each portionbeing formed in its meeting face with a horizontal groove, the groove of the projecting portion and the groove of the seat portion con ointly forming a pivot-supporting seat, and a knife edge pivot supported in each seat, the knife edges of the pivots respectively proj ecting upwardly and downwardly and being disposed in parallelism and in the same horizonta'l plane, the knife edges of one pair of pivots on one core being maintained in longitudinal alinement with the knife edges of the other pair of pivots on the other core.

5. A dry sand core for supporting scale lever knife edge pivots comprising upper and lower sections having their meeting faces formed to provide a projecting portion and a seat portion, the meeting faces of said portions being respectively provided with grooves conjointly forming horizontal seats, the 10 groove of each projecting portion being V- shaped in cross-section, and a knife edge piv- 0t supported in each seat with its knife edge positioned in the associated V-shaped groove.

In testimony whereof I hereunto 'afiix my 15 signature.

ANTHONY PEARSON HOPKINS. 

